Dual air doctor for paper coating machines



A ril 25, 1961 E. P. OLSZOWKA DUAL AIR DOCTOR FOR PAPER COATING MACHINES 2 Sheets-Sheet 1 Filed March 51, 1960 I IIII 1? OLszowm April 25, 1961 P. OLSZOWKA 2,931,223

DUAL AIR DOCTOR FOR PAPER COATING MACHINES Filed March 31, 1960 2 Sheets-Sheet 2 DUAL AIR DOCTOR FOR PAPER COATING MACHINES Edward P. Olszowka, St. Catharin assiguor to Howard real, Quebec, Can

Filed Mar. 31, 1960, Ser. No. 18,975 8 Claims. (Cl. 118-63) es, Qntario, Canada, Mills Limited, Mont- This invention relates to an ing machines of the t sheet of paper and an ing material by blowi thin, high velocity stre the fluid coating on the pap It has been found the velocity of highly critical improvement in paper coatype comprising a moving web or air doctor for distributing the coatng on the freshly coated paper a gaseous fluid which smoothes in practice that the pressure and the air stream as it hits the paper are pt at precisely constant f satisfactory results depend directly on octor orifice fromthe paper and close to the newly coated ating fluid gradually cover the orifice and after a period of variation of the air pressure and When this happens, the coatand the machine must be and readjust the air doctor. oss of production.

bviates the above-mentioned machinery by providing two alternatively placed in operag the inactive one to be re adjusted when necessary withation of the machine. Whenconditioned unhurriedly,

and kept ready to replace the second air doctor whe n the latter in turnbecomes In accordance with the inven are symmetrically mounted tion the two air doctors doctors, to ensure that th proper location with resp Preferred embodiments by way of example in e operating air doctor is at a cot to the paper.

of the invention are illustrated the accompanying drawings, in

Fig. 1 is a verti doctors taken on 1i Fig. 2 is a fra of the apparatus i Fig. 3 is a side Fig. 4 is a ve Fig. 1, showing place one air do Fig. 5 is a sid trating an altern ing the carrier cal section of an arr ne I-I of Fig. 3; gmentary pers angement of air pective View of one end elevation in the operative position;

en on line IVIV of g rotated to rertical section tak the carrier as it is bein ctor with the other;

e elevation corresponding to Fig. 3, illusative embodiment of the means for movbetween operative and disengaged posig to Fig. 3, numeral indicates the main e paper coating machine, which has a breast tion is shown schematically at 11, and

which supports a web or sheet 12 of paper to which coat- 5 either end of the roller 11-.

position of Fig. 1 is ing material has been or a bath (not shown). The paper 12 moves continuously in the direction of arrow 13.

Brackets 14 are attached to the main frame 10 beyond On each bracket is mounted a saddle 15 having a keyway slot on its bottom face registering with a similar slot on the topv face of the bracket, the slots having fitted therein a key 16 (Fig. 1). Each saddle 151's secured to the corresponding bracket 14 by screws 17 (Fig. 3) which engages slots 18 (Fig. 2) on the base of the saddle; the arrangement is such that the saddles 15 are kept in breast roll 11 by the keys 16, but their spacing from the roll can be adjusted, in particular to set the two saddles parallel with the roll. the two saddles 15 are are tightened; this adjustment is final and it need never be varied during the operation of the machine.

Each saddle 15 comprises a slideway formed of a bed 19 integral with the saddle and of a bridge 20 (Fig. 2) secured across two upright walls .21 and 22 (Fig. 3). Slidably mounted between the bed 19 and the bridge 20 of each saddle is a lelepiped. A shaft 24 (Fig. 1) interconnects and is rotatbreast roll by abutment of the blocks with the ends of adjusting-screws 28 threadedly engaging walls 22 (Fig. 3). and secured in position by counter-nuts 29.

A pair of carriers 30 (Fig. l) in the form of hubbed plates are rotatably mounted on the shaft 24 internally adjacent the bearing blocks 23, by means of bronze bear-f lugs 31. Each carrier has two opposite semicircular recesses symmetrical with respect to the axis of a shaft 24, in which recesses fit end bushings 32 (Fig. 3) which are secured to the ends of the two air doctors 33 (Fig. 1); the bushings 32 at one end comprise keys 34 (Fig. 1) which fit in appropriate slots of the recesses of the carriers 30 to keep the air doctors in their proper position. The bushings 32 are secured to the carriers by clamps 35.

The air doctors are of generally conventional construction which can best be seen by reference to Fig. .2. As shown therein each air doctor 34 comprises a main-body which is hollowed out to form a plenum 36, and to which are secured lips 37 and 38 which define a thin elongated orifice between them.

Each carrier 30 has on opposite sides thereof, symmetrical with the axis of shaft 24, two slots 39 (Figs. 2 and 4) having their lip portions 48 slightly bevelled and upright walls 22, to secure the carrier and doctor 'assem-. bly in a fixed-angular position.

Each saddle 23 has a hole 4 2 (Fig. 2) under the bed 19; a bushing 43 (Fig. 1) fitted to the ply duct 44 is secured in each hole 42 by means of bolts 45.

on a flange d7 of a nipple 48 which projects externally of hole 42; the nipple 48 has its externally projecting portion 49 sliding in a restricted end portion of the hole 42, this end portion defining a shoulder 50 which in the' spaced from the flange 47. The

Patented Apr. ,25, 1961 applied by means of applicators planes perpendicular to the When the apparatus is first set upso adjusted and the cap screws 17' ings 32 therefore push nipple 48 also comprises an internally extending portion 51 in telescopic engagement with the wall of the bushing 43. The nipples 48 have their axes at the same distance from the axis of shaft 24 as the axes of end bushings 32 of the air doctors, so that these bushings maybe made to register with the nipples. Both bushings and nipples have slightly chamfered edges to facilitate engagement between them.

The bearing blocks 23 may be firmly secured in any position by means of bolts 52 (Fig. 1) having their heads 53 fitting in round holes in the top faces of the hearing blocks. Each bridge 20 comprises a slot 54 (Fig. 2) opening into a groove 55 (Fig. 1) in the bottom face of the bridge. The bolt 52 on each side comprises a square or rectangular collar 56 of thickness smaller than the depth of the groove 55 and fitting therein; the threaded portion 57 of each bolt extends through the slot 54 and is engaged externally by a hand nut 58.. T ightening of'the nuts 58 secures the bearing blocks 23 against movement.

The shaft 24 has its portion between the carriers 30. encased by a tubular sheath 59 which is secured to the carriers and acts as a permanent spacer between them for when both doctors are removed.

The operation of the apparatus described above is as follows:

After the saddles 14 have been set parallel and the cap screws 17 have been tightened, the adjustment screws 28 are set to obtain a desired spacing between the lips 37 and 38 of the air doctors and the paper web 12 supported by the breast roll 11, when one of the air doctors 33 is in the operative position shown in Fig. 3. In this position the bearing blocks 23 abut the ends of screws 28 and corresponding slots 39 of each carrier engage the tenons 41. During operation the hand nuts 58 are tightened so as to prevent any movement of the air doctor and carrier assembly.

When the operating air doctor becomes clogged the two hand nuts 58 are loosened, one of the hand wheels 25 is turned thus rotating the shaft 24 which travels away from its position 24 (Fig. 4) due to the action of pinions 26 cooperating with racks 27, until the slots 39 are clear of the tenons 41 (position of Fig. 2). The air doctor and carrier assembly is then rotated through 180 degrees, as shown in Fig. 4, and the hand wheel 25 is turned in the opposite direction, causing return of the shaft and associated parts towards the breast roll, and engagement of the opposite slots 39 with the tenons 41. The return movement is stopped by abutment of the bearing blocks 23 against screws 28. This position is again identical to that of Fig. 3, since the air doctors are symmetrical with the axis of rotation of their assembly, and the spacing of the new air doctor which is in operative position, from the web of paper, is identical to the spacing of the other air doctor which was formerly in operative position. Finally the hand nuts 58 are tightened.

As either of the air doctors 33 comes to operative position it engages with its bushings 32 the nipples 48 which, during the changeover, project slightly inwardly of their position shown in Fig. 1, due to the action of springs 46 which force flanges 47 against shoulders 50. The bushthe nipples 48 outwardly against springs 46, so that when the air doctor is in position and the bushings register with the nipples, a sealing engagement is produced. The air under pressure supplied to the plenum 36 through the air ducts 44 will not, therefore, leak out at this point.

It can be seen that the above described operation of replacing one air doctor with the other can be carried out very quickly (it) to 15 seconds) without stopping the machine or disconnecting the air supply. Once the changeover has taken place, the inactive air doctor is easily attainable for cleaning or replacement and readjustment.

The alternative embodiment illustrated in Fig. differs from that described above only in that the pinion and rack arrangement is replaced on each side by two levers 60 and 61 which are pivotally interconnected at 62, the lever 60 being secured to shaft 24 and the lever 61 being pivotally connected at 63 to the slightly modified saddle 15'. Turning of the shaft 24 causes angular displace ment of the levers 60 which under the control of the levers 61 move the bearing blocks 23 away from or towards the breast roll 11 as required. The operation of this alternative embodiment is identical to that of the first embodiment of Figs. 1 to 4.

The invention is limited not to the above embodiments, but only by the scope of the appended claims.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. In a paper coating machine, in combination: a hearing means mounted for translation, a carrier rotatably mounted on said bearing means, a pair of air doctors mounted on said carrier symmetrically with respect to its axis of rotation, a pair of slots on said carrier symmetrical with its axis of rotation, a tenon fixed with respect to said machine and engageable with said slots by translation of said bearing means to secure said carrier in two predetermined angular diametrically opposite positions with respect to said machine, each position corresponding to the engagement of one of said slots by said tenon.

2. In a paper coating machinehaving means for supporting a moving paper web of substantial width, in combination: a bearing means mounted at each side. of said supporting means, means slidably mounting said bearing means for movement towards and away from said paper web, means interconnecting said bearing means for parallel movement thereof, a carrier rotatably mounted on each of said bearing means, said carriers having a common axis of rotation, a pair of air doctors mounted between said carriers symmetrically with respect to the axis of rotation of said carriers, a pair of slots on each carrier symmetrical with its axis of rotation, a tenon at each side of said supporting means fixed with respect to said machine and engageable with the slots of the corresponding carrier by sliding movement of said bearing means to secure said carriers in two predetermined angular diametrically opposite positions with respect to said machine, each position corresponding to the engagement of corresponding slots of each pair by said tenons.

3. In a paper coating machine having a breast roll for supporting a moving paper web of substantial width, in combination: a bearing block mounted at each end of said roll, saddles for slidably mounting said blocks for movement towards and away from said paper web, a shaft rotatably mounted in said bearing blocks, pinions secured to said shaft at either end thereof, racks fixed with respect to said machine and meshing with said pinions whereby rotation of said shaft causes parallel movement of said bearing blocks, a carrier fixed to said shaft adjacent each bearing block, a pair of air doctors mounted between said carriers, symmetrically with respect to the axis of said shaft, apair of slots on each carrier symmetrical with the axis of said shaft, a tenon at each end of said roll fixed with respect to said machine and engageable with the slots of the corresponding carrier by sliding movement of said bearing means to secure said carriers in two predetermined angular diametrically opposite positions with respect to said machine, each position corresponding to the engagement of corresponding slots of each pair by said tenons.

4. In a paper coating machine having a breast roll for supporting a moving paper web of substantial width, in combination: a bearing block mounted at each end of said roll, saddles for slidably mounting said blocks for movement towards and away from said paper web, a shaft rotatably mounted in said bearing blocks, a pair of pivotally interconnected levers, one lever of each pair being pivotally mounted on each of said saddles and the other lever of each pair being secured to said shaft, whereby rotation of said shaft causes parallel movement of said bearing blocks, a carrier fixed to said shaft adjacent each bearing block, a pair of air doctors mounted between said carriers symmetrically with respect to the axis of said shaft, a pair of slots on each carrier symgageable with the slots of the corresponding carrier by sliding movement of said bearing means to secure said carriers in two predetermined angular diametrically opposite positions with respect to said machine, each position corresponding to the engagement of corresponding slots of each pair by said tenons.

5. in a paper coating machine having a breast roll for supporting a moving paper web of substantial width, in combination: a bearing block mounted at each end of said roll, saddles for slidably mounting said blocks for movement towards and away from said paper Web, a shaft rotatably mounted in said bearing blocks, means connected to said shaft to cause translation thereof when it is rotated whereby said bearing blocks are mounted for parallel movement, abutments limiting movement of said bearing blocks towards said paper web adjustably mounted on said saddles, a carrier fixed to said shaft adjacent each bearing block, a pair of air doctors mounted between said carriers symmetrically with respect to the axis of said shaft, a pair of slots on each carrier symmetrical positions with respect to said machine, each position corresponding to the engagement of corresponding slots of each pair by said tenons.

6. In a paper coating machine, the combination according to claim 5, further comprising means for releasably fastening said bearing blocks to said saddles.

7. In a paper coating machine the combination accordingto claim 5, wherein each block comprises a hole, each saddle comprises a slot, and a bolt is mounted with its head fitting in said hole, said bolt extending through said slot and having a nut to fasten said bolt to said slot, for releasably fastening said bearing blocks to said saddles.

8. In a paper coating machine having means for supporting a moving web of paper, 1n combination: a rotat- References Cited in the file of this patent UNITED STATES PATENTS 2,766,720 Muller Oct. 16, 6 

